Liz Hall, of Albany, N.Y., digs her car out of snow in the Center Square neighborhood.

PHILADELPHIA (USA TODAY/AP) --Millions of residents in the South and Northeast are hoping for winter relief by late Friday afternoon, as the latest deadly snow and sleet storm system to batter the region courses its way through New England and into Canada.

The lingering storm is responsible for at least 21 deaths so far, about 14,000 canceled flights and snarled traffic from the deep South to upper New York State. The chilling impact remains: lost retail sales, less worker productivity and stressed parents, frazzled by another day of youngsters home-bound by canceled classes in at least nine states. Many will have an extended weekend due to Monday's closures for Presidents Day.

The National Weather Service forecast improving conditions in the Mid-Atlantic region Friday afternoon as the Nor'easter courses swiftly through New England. Light snow and rain are expected. But the storm's impact was still being felt in the Mid-Atlantic, blanketed with up to two feet of snow. A series of crashes involving dozens of cars and trucks jammed traffic along portions of the slickened state Turnpike near Bucks County, Pa., early Friday.

Hopes that Mother Nature might lighten up on Valentine's Day failed to mend the soured relationship between NBC meteorologist Al Roker and New York City Mayor Bill de Blasio over the mayor's decision to keep schools open Thursday. City schools have been closed for snow fewer than a dozen times since the 1970s.

Roker blasted de Blasio in a series of tweets for his criticism of the Weather Service. Roker hasn't backed off, but Friday morning, he apologized on the Today show for tweeting "one term" for the newly elected mayor.

New York was hit by 10 inches of snow. Storm-related deaths included Min Lin, 36, who was killed by a snowplow in a shopping center in Brooklyn. Her nearly full-term baby was later delivered by cesarean section at a medical facility, where the baby is listed in critical condition.

More than 1 million homes and businesses were without power Thursday, but that fell to about 440,000 Friday morning, mostly in South Carolina and Georgia, where more than 100,000 customers remain without service in the Augusta area. Black ice kept roads hazardous, although temperatures are expected to hit the mid-50s by Friday afternoon.

Washington, D.C., virtually shut down by nine inches of snow Thursday morning, picked up another three inches Thursday night. Federal offices were reopening, but many schools remain closed.

Officials in several states continue to warn about storm hazards. Two suburban Maryland men died after shoveling snow.

Winter storm warnings were lifted in parts of the South, although some regions were expecting up to four inches of snow by Friday evening. In Kentucky, the congregation of Calvary Baptist Church at Pinetop was mourning the death of the Rev. Carlos Craft, 73, killed when the vehicle he was using to clear snow slid into a creek.